Disposal of solid waste is a nationally recognized problem. Conventionally, solid waste is placed into a ground void more commonly referred to as a land fill. Most land fills are nothing more than a dumping ground for non-separated waste including plastics, aluminum, glass and other none bio-degradable matter, consuming valuable space. Some land fills are designed to "compost" organic matter over a period of time by creating a digestive environment. Despite the type of land fill employed, in the United States it is well known that the rapid increase in general population produces waste at a level that exceeds the capacity of present land fills. The current state of land fills is best described as critical, with the prediction that all existing land fills will be filled before the turn of the century.
New sites for land fills are limited. The general population has expanded at such a rate that land once thought available for use a land fill may now be surrounded, if not covered, by housing. Further, the continuing awareness of ground water contamination, methane gas production, decreased property values, and general pollution resulting from land fills requires each proposed site to undergo extensive debate as well as meet strict environmental standards.
In response to these problems, incineration of waste has gained limited acceptance, but the associated air pollution constitutes a major drawback. In addition, the by-product of incineration consists of ash that is typically considered a hazardous waste. Recycling is an effective alternative in lessening the proportion of biodegradable material placed in land fills, and is now required by law in some areas. Composting of waste is also a viable alternative to conventional dumping with variations using some forms of incineration, recycling, and composting being the subject of numerous patents.
Composting systems use aerobic mixing to control composting parameters such as pH, moisture content, temperature, and oxygen levels of a compost mixture. Typically, composting is carried out in economical windrow piles. However, the windrow is a static pile of non-uniform depth, does not provide uniform composting, and requires undesirably large sections of land.
The temperature distribution at the surface of the pile is significantly less than the temperatures at the center of the pile. The windrow is spread across a length of land and if the pile is high in leachables, such as nitrates, the pile may lead to ground water contamination.
Composting by windrow requires mixing for aeration. A "SCARAB" machine is commonly used to straddle the pile to fluff and aerate the compost. If the mixing is performed infrequently, the pile can produce a severe odor problem from anaerobic pockets. Frequent mixing destroys digestion and further increases the spore levels around the pile. Conventional practice requires a windrow to undergo a 30 to 45 day aeration/non-aeration curing period when mixing is employed.
What is needed in the art is a method and apparatus which effectively accomplishes composting over a short period of time without utilization of expensive real estate, equipment, or require a high operational expense. One attempt at addressing this issue is disclosed in U.S. Pat. No. 4,956,002 issued to Egarian regarding a process for composting organic waste utilizing modular containers. Each container is placed side by side, interconnected, each dependent upon the other for the process. Extensive monitoring is required to determine the progress of the composting.
U.S. Pat. No. 4,483,704 issued to Easter discloses a method of composting sludge employing the use of a silo. Treated sludge is placed at the top of the silo while composted material is withdrawn from the bottom of the silo. The process simply moves the sludge from the top to the bottom of the silo, the composting process taking place therebetween.
The prior art does not teach a method of composting which can effectively be completed for certain of the waste material over approximately 14 days by vertical stacking of modular containers, nor does the prior art teach a method or apparatus allowing composting without forced aeration, mixing, or elaborate monitoring controls. It is to the effective resolution of the aforementioned problems that the method and apparatus of the instant invention is directed.